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xJake Registered Member

Join Date: Nov 2006 Posts: 1,385

IIRC, the main benefit of actinic lighting in a captive reef aquarium setting is for the purpose of coercing your corals to produce fluorescent pigments and subsequently display better coloration.

Actinic lighting, as the name suggests, produces mostly UV radiation. Corals can only tolerate so much exposure to UV radiation, and subsequently produce fluorescent proteins for the purpose of reflecting excess UV radiation away from their tissues. They can and do use UV ("actinic") lighting for photosynthesis, but as I stated, they can only be exposed to a certain intensity before it begins to damage their tissues. Some corals are able to produce these UV reflecting pigments quite easily, but many species are not quite as adept at performing this process.

From what I have read, most metal halide lighting produces a level of UV radiation that is sufficiently equivalent to (or in many cases greater than) that of natural sunlight. Subsequently, if you are using high intensity metal halide lighting, actinic supplementation becomes virtually pointless (in terms of the health of the coral, and/or reproducing "natural" lighting conditions).

On the other hand, as stated by others, actinic lighting, when used alone, produces an extremely awe-inspiring display of the fluorescent pigments that your reef organisms naturally produce, and this can be a very rewarding method of viewing your corals. Many people find this type of viewing reason enough to spend the money on additional actinic supplementation, but in terms of maintaining coral "health" I personally don't find it to be necessary.

I believe there is a chapter in The Reef Aquarium Vol. 1 by Delbeek and Sprung (10 or 11, or whichever is the chapter entitled "Lighting") that goes into this topic in depth, and I would suggest looking to that source for further information.

Actinic Light vs. Blacklight – Highlighting Fluorescent Livestock and Decor

With the growing popularity and availability of fish like GloFish and GloTetras and decorations like our own Pure Aquatic Glow Elements line, “glow-in-the-dark” and fluorescent aquariums are becoming more and more common. Most of these animals and decorations are brightly colored in any light but under special lighting, the colors will really glow. There are two main kinds of light that are used in these aquariums: “blacklights” and actinic lights. Knowing the difference between these two can play an important role in making your tank really stand out, as well as in keeping it healthy. For this blog, we will be focusing in general terms only for community aquariums. Aquarium with invertebrates and corals will have different needs since their light requirements are much more specific and extensive.

First, the science…

The colors we see around us come from the light’s wavelength, measured in Terahertz (THz) or nanometers (nm). Most people can see light ranging from about 700nm (reds) to about 400nm (purples). Blacklights and actinic lights both produce light from the bottom of the visible light spectrum (the BIV in ROY G BIV). Most actinic lighting for aquariums has a wavelength of about 420-460nm. The higher end of this range (460nm) produces a more blue color light, while the color shifts to purple approaching the lower end (420nm). This type of lighting is still well within what we are capable of seeing. “Blacklights” emit a light below what we as humans are able to see known as ultraviolet or UV light. Yes, this is the same UV light that we wear sunscreen to protect ourselves against! UV lighting is separated into three major ranges. Blacklight bulbs are UV-A bulbs (315-400nm), the spectrum which causes our skin to tan. For comparison, the UV Sterilizers popular in aquariums for eliminating algae, diseases and parasites are UV-C bulbs (200-280 nm), a destructive spectrum that is mostly filtered out by Earth’s atmosphere and the UV-B range in between is the more damaging rays from the sun that causes sunburn and other harmful conditions.

Right now, some of you may be saying “But I can see when a blacklight is on….its purple!”. Not exactly. The color you see when a blacklight is on is a by-product of the UV production itself. In order for a light bulb to function, a chemical phosphor inside the glass is ignited. This produces the radiation, but it also produces visible light so a filter is used on the bulb itself to block some of this light. This filter changes the wavelength slightly so it is dampened to about 370-400nm, a range which we can start to see as a purplish or dark blue glow. Think of it like lighting a fire to heat a room; the flame also gives off light as well as heat and you may put a screen in front of it to block the light and protect yourself from the flames. Unshielded UV bulbs are used in bug zappers to attract insects to their demise.

Now, back to your aquarium…

Making the choice between using actinic or blacklights for your glowing aquarium depends on when or how you would like to view it. Fluorescent bulbs and LED fixtures are both available with a variety of actinic and blacklight option. Both actinic lights and blacklights make things glow when the light they produce is reflected off of the fluorescent pigments in the object, whether this is light we can see (actinic) or light we can’t (blacklight). These pigments could be in the artificial coloration of an ornament or plants, or in the proteins or cells of a living creature, either artificially or naturally. Many plants and animals that we don’t think of as “glowing” have pigments that are fluorescent under the ultraviolet range. This can help them to blend in or stand out to other animals that can see this range that we can’t. Fish like GloFish have been enhanced with proteins from these fluorescent creatures at their embryotic stages so they can share in these glowing traits.

For daytime viewing, an actinic light is a better choice since it produces more of a brighter light that we can see and less UV radiation that can be harmful to some more sensitive organisms in higher concentrations. Blacklights are a good option for nighttime viewing only, when you may not want to see anything in the aquarium other than those fluorescent glowing objects or fish. You may choose to use one or the other of these lights or a combination of them or more standard “white” lighting which contains a balance of the entire visible light range. Lighting an aquarium containing glowing elements with a more traditional white light or “50/50 bulb” (half white light, half actinic) during the day and changing to an actinic or blacklight at night can truly give you a dramatic change to the look of your aquarium with no more effort than the flip of a switch!

Actinic Lamps at Home Depot?

Years ago, while on a trip to the west coast, I heard that a local Home Depot home improvement store stocked ‘blue’ metal halide lamps. The person telling me this had not actually seen them, but a friend of his had. I did not have the opportunity to confirm the story, but figured if it was true, that all Home Depot stores would eventually stock them. As you have likely guessed, this story falls into the Urban Legend category as I have never seen any sort of specialty metal halide lamp in any of HD’s stores. However, I can say that Home Depot sells small compact fluorescent lamps (CFLs) that appear to be ‘actinic’ lamps. Feit Electric (Pico Rivera, California) markets these CF lamps as ‘EcoBulb PartyBulbs’. They are advertised to use only 13 watts and have a life expectancy of 7 years/8,000 hours.

These lamps are small in size, contain an internal ballast and have a standard ‘screw-in’ mogul base. But are these suitable for lighting aquaria? How much light do they produce, and how does the spectrum compare to a ‘true’ actinic lamp? There are other lamp colors available – a ‘black light’, green, yellow, red as well as warm white, soft white and 6500K daylight. At only $4.99 each (Hawaii price), I picked up several for testing purposes. The 13 watt 6500K ‘daylight’ CFLs were found at the local Wal-Mart and I picked up a package for testing as well.

Feit’s website offers little information on these lamps, and certainly no spectral data other than stating the obvious color. Once again, I realized that analyses of these lamps would require use of quite a bit of laboratory equipment and software.

The first order of business established the spectral quality of each of these lamps. If these lamps were merely coated with a material that selectively filtered the output of a, say, warm white lamp, this would be immediately obvious. On the other hand, if the lamps’ phosphors were those to produce relatively narrow bandwidths, further testing could begin.

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Spectral Quality

Spectral quality of these lamps was measured with an Ocean Optics USB2000 spectrometer (see the ‘Testing Protocol’ section below for details).

Note: Disregard the y-axis (Relative Intensity) in the following ‘Spectral Quality’ charts. It is irrelevant as the distance of the lamp above the spectrometer patch cord was not standardized. Intensity (reported as Photosynthetically Active Radiation, and tested under standardized conditions) will follow later in this article.

Feit Ultraviolet-A (or Black Light) Compact Fluorescent Lamp

As Figure 2 shows, this lamp is a true ‘black light’ and most of its output is in the UV-A portion of the spectrum.

Table 1. Breakout of the Feit black light. Color Percent UV-A 92.0% Violet 3.9% Blue 1.7% Blue-Green 0.1% Green-Blue 0.2% Green 0.3% Yellow-Green 0.7% Yellow 0.2% Orange 0.1% Red 0.9%

ProLume 15 watt Black Light

The spectral qualities of the ProLume CFLs are practically the same as the Feit lamps. See Figure 4.

Feit Blue Compact Fluorescent Lamp

This lamp was of the most interest to me personally. Results of testing showed it to produce most of its radiation in the violet and blue bandwidths.

Table 2. Breakout of the Feit blue light. Color Percent Violet 21.7% Blue 71.0% Green-Blue 3.0% Blue-Green 2.3% Green 0.7% Yellow-Green 0.8% Yellow 0.1% Orange 0.0% Red 0.3%

Feit Green Compact Fluorescent Lamp

This is an interesting lamp, and this lamp is not generally offered to aquarists. Very little of its output is absorbed by Chlorophyll a, Chlorophyll c 2 , or the accessory pigment peridinin, all of which are found in corals’ symbiotic algae (zooxanthellae). However, it may have an application for hobbyists, as we will discuss later.

Table 3. Breakout of the Feit green light. Color Percent Violet 0.6% Blue 2.1% Green-Blue 1.5% Blue-Green 16.0% Green 34.8% Yellow-Green 39.5% Yellow 3.5% Orange 1.1% Red 1.0%

Feit White ‘Daylight’ (6500K lamp) Compact Fluorescent Lamp

The output of a ‘daylight’ lamp is not as flattering to those of us vainly observing our skin tones in a mirror. Its output is harsh in comparison to ‘warm’ or ‘soft’ white fluorescent lamps, thus they are considered something of a specialty lamp.

However, I found these at Wal-Mart in a package of three for a reasonable price.

Table 4. Breakout of the Feit 6500K ‘daylight’ lamp. Color Percent Violet 6.7% Blue 27.0% Green-Blue 5.5% Blue-Green 5.6% Green 3.9% Yellow-Green 22.8% Yellow 2.5% Orange 5.0% Red 21.0%

Feit Soft White Compact Fluorescent Lamp (~2700K)

This lamp produces a warm, pinkish light and is generally preferred for use in living areas and bathrooms. These produce less blue, but more red, light than ‘daylight’ lamps.

Table 5. Breakout of the Feit ‘soft white’ light. Color % Violet 7.2% Blue 8.8% Green-Blue 3.5% Blue-Green 1.6% Green 0.4% Yellow-Green 27.3% Yellow 4.6% Orange 7.8% Red 38.8%

Lamp Intensity

The amount of radiation (Photosynthetically Active Radiation, or PAR, reported in units of micromol per square meter per second, or molm²sec) was determined through use of a LiCor quantum meter and sensor. See the ‘Testing Protocol’ section below for details.

PAR varied wildly among types of lamps. See Figure 13.

We should recall that the light output of fluorescent lamps is dependent upon operating temperature. During testing, it was noted that light intensity increased for the first minute or two of operation then fell before reaching a steady-state plateau. This indicates that passive cooling is insufficient to keep the lamp output at its maximum.

Horizontal versus Vertical Operation

These lamps are ‘universal burn lamps’, meaning that they can be operated horizontally, vertically, or any angle in between. I was interested in which position (vertical or horizontal) would ‘throw’ the most light. See Figure 14. While I had the lamp in the horizontal position, I placed a hemispherical aluminum reflector above it and evaluated its effect on focusing light downwards (shown also in Figure 14).

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A crude aluminum reflector effectively focused PAR, but not to levels useful for illuminating most reef aquaria.

As can be seen, the reflector effectively doubled the amount of light falling upon the PAR sensor. Still, a PAR value of only 64 molm²sec would be of little practical use for most reef aquaria. But what of other types of reflectors?

Effects of Pendent Reflector Geometry on Light Intensity

I purchased the reflectors shown in Figure 15 during a trip to Honolulu a few years ago, and I have unfortunately lost all information on them. They were sold ‘loose’ (not in a box), and I suspect these can be obtained through any reasonably-well stocked lighting store.

The sizes of the reflectors in Figure 15 are (from left to right):

Reflector A: 2.5″ diameter X 3.25″ high (top diameter is 1.75″)

Reflector B: 3.75″ diameter X 2.75″ high (top diameter is 1.375″)

Reflector C: 3.75″ diameter X 3.75″ high (top diameter is 2.25″)

Of these, the last on the list was most effective in that the top diameter is large enough to allow more latitude in positioning over the lamp (the diameters of these CFLs are about 1.75″). I found the best light intensity when the top of the reflector was even with the bottom of the ceramic base.

Using the same reflector (‘C’) on the Daylight 6500K lamp, I found the maximum intensity was also increased by an order of one magnitude (that is, from about 95 to almost 1,100 molm²sec).

Power Consumption

These lamps are advertised to consume 13 watts of energy, and replace a 60 watt incandescent lamp. The claims of energy consumption are reasonable (if slightly overstated). Only the Daylight and Soft White lamps produce enough light to be true replacements for 60 watt incandescent lamps.

Heat Transfer

Fluorescent lamps are designed to operate at relatively narrow ranges. Although the advertising tells us the lamp can operate from -10°F to 140°F, this does not necessarily mean that light production is at its highest. Light production is dependent upon pressure of the mercury vapor within the lamp, and pressure is dependent upon temperature. Many fluorescent lamps are designed to operate at a temperature of about 100°F. In any case, these lamps operate at a temperature of ~69°F to ~165°F, depending upon where on the lamp the temperature is taken with the non-contact ‘heat’ detector. Figure 18 shows transfer of heat to an I-button temperature data logger (this is the difference, or delta, between a control data logger placed away from the lamp and the data logger placed 3.5″ below the CF lamp).

Is this really important? See article for details.

After data were gathered for Figure 18, I experimented with various reflectors, and found that the lamps can be further removed from the aquarium water surface while increasing (focusing) the amount of PAR. I did not repeat the temperature experiment but feel confident that heat transfer will not be a serious concern when using pendant-type reflectors, although some means of cooling should be provided.

Lamp Life

Manufacturers base lamp life on tests meeting certain criteria and is generally calculated when the number of failures reaches a given percentage (usually 50%) in a large sample of lamps. The manufacturer does not care if the amount of light produced by the lamp has dropped, only that the lamp still ‘burns’.

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Feit prominently advertises their CFL lamps will last 7 years, but the fine print tells us this is based on ‘household’ usage of 3 hours per day (or 7,665 hours, which is reasonably close to the advertised 8,000 hours of expected life). Realistically, these lamps will lose intensity and likely have a useable life expectancy similar to other fluorescent lamps (perhaps 6-12 months when burned for 12 hours per day, or 2,000-4,000 hours).

All fluorescent lamps lose intensity partially due to ‘sputtering’ – the vaporization of the electrodes which coats the internal surfaces with metallic materials. This causes the dark rings at the ends of standard fluorescent tubes.

Disposal of Used Lamps

All fluorescent, metal halide and mercury vapor lamps contain the element mercury (Hg). The amount of mercury is very small and recommended disposal procedures are often the same as those for regular incandescent bulbs, however, use of any of the internet search engines can provide local regulations. The EPA does not regulate disposal of mercury lamps unless you generate a lot of used lamps.

Discussion and Conclusions

I did not have high expectations for these lamps when I purchased them. But even after making close to 100,000 light measurements over the course of the last 15 years or so, I realize that I can still be surprised.

Although the Feit ‘blue’ lamp does not possess the same spectral characteristics of a ‘true’ actinic lamp, it is remarkable close. See Figures 19 and 20.

However, the light quality of the daylight lamp is about equal to any daylight lamp on the market. The Feit ‘green’ lamp likely has applications when one wishes to mimic turbid reef environments, though they will have to be mixed with daylight and/or actinic lamps to gain PAR and aesthetic value. Interestingly, the output of the green lamp possesses wavelengths known to enhance red and orange fluorescence in at least some coral species. Black lights have applications in specialty aquaria, especially where the goal is to showcase most any of the fluorescent pigments found in so many corals.

The amount of PAR produced by the daylight and soft white lamps is very good for a low-wattage lamp. The green and blue lamps, when not housed in a reflector, produced a disappointing amount of light. However, selective use of a quality reflector and lamp positioning makes these lamps worthy of your attention. It is not difficult to imagine a number of these lamps wired in series and housed in proper reflectors projecting enough light into a shallow nano-reef or specialty tank (such as a refugium or frag tank). Such a luminaire would be inexpensive to build and operate, and lamp replacement cost would be minimal. These are factors we rarely encounter when dealing with reef aquaria and could be easily exploited to the advantage of hobbyists possessing basic carpentry and electrical wiring skills.

Obviously, care should be taken to avoid water splashing on these or any other electrical devices. When designing your luminaire, consider use of clear acrylic material to shield the lamps from splashes and/or salt spray. This, in turn, will require the use of some sort of non-passive cooling such as a small computer fan. Keeping the lamps cool is important and should increase lamp longevity and PAR/spectral output.

There are some drawbacks – these lamps are not dimmable, and are not recommended for use with timing devices (since these tend to shorten the life of the lamp). However, these specialty lamps should lend themselves well to applications devised by an enterprising hobbyist. Replacing these lamps every six months (~2,000 hours of operation) should not be a difficult or expensive endeavor.

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Warranty

Feit warranties their lamps according to type of use. ‘Commercial’ use is for1 year, and ‘Household’ (use of 3 hours per day) is guaranteed for a period of 2 years. At $5 a pop, should we really be concerned about a warranty?

Testing Protocols